Enhancing the Disintegration and/or Degradation of a Smoking Article

ABSTRACT

A filter ( 2 ) for a smoking article ( 1 ) is provided by the present invention, the filter comprising a vehicle containing a liquid capable of enhancing the disintegration and/or dispersibility of the smoking article. A method of enhancing the disintegration and/or degradation of a smoking article is also provided, wherein the smoking article comprises a vehicle containing a liquid capable of enhancing the disintegration and/or degradation of the smoking article.

The invention relates to enhancing the disintegration and/or degradationof used smoking articles, and particularly, but not exclusively, toenhancing the disintegration and/or degradation of the filter of suchsmoking articles.

A problem with currently available tobacco smoke filters, particularlycigarette filters, is that they can be difficult to dispose of afteruse.

During smoking most of the tobacco rod and its circumscribing paperwrapper are converted to gases and ash in an incineration process. Theremaining components of the spent smoking article include a smallportion of ash, part of the original tobacco rod and wrapper, and thefilter which is made up of the filter plug, plugwrap, and tipping paperwrapped about the tobacco rod and filter. There are also adhesivespresent that secure these components together. Spent smoking articlesare generally completely dissociated into their individual constituentparts within a relatively short period of time when exposed to moisture,and/or mechanical abrasion. The individual components of the spentsmoking articles are thus subsequently able to disperse and degrade.

The plug of filter material, however, typically does not readilydisperse or degrade. With limited exceptions, filters are presentlyformed from highly crimped cellulose acetate fibres bonded at theircontact points using plasticizers to provide a significant volume ofinterstitial space for the passage of smoke. The bonded contact pointsof such filter elements degrade very slowly under normal environmentalconditions. The cellulose acetate fibres are themselves generally poorlybiodegradable.

Despite the developments to date towards improving the biodegradabilityof filter plugs, there is interest in improved techniques for producingfilters having an enhanced biodegradation rate. At the same time, thereis also a need to retain the filtration chemistry, smoke characteristicsand consumer acceptability provided by currently available smokingarticle filters.

In order to produce smoking articles, including filter cigarettes, whichare more easily disintegrated or dispersed and are more biodegradable,it is desirable to provide a smoking article displaying a relativelyrapid dissociation of the individual components of the spent smokingarticle followed by a good rate of dispersion and biodegradation of theindividual components. In other words, increasing the rate ofdissociation of a spent smoking article enhances the rate of degradationby increasing the exposure of the individual components to naturalelements such as moisture, sunlight, mechanical abrasion, and aerobicbiodegradation.

One approach that has previously been used to improve the dissociationof spent smoking article filters involves the incorporation of waterexpandable gels in the filter material to swell the filter upon contactwith moisture and thereby break open the filter tipping paper to exposethe filter material to the elements.

It has also been suggested to manufacture the components of a smokingarticle filter, including the filtration material, the filter plugwrap,and the tipping paper, from a moisture disintegrative paper. The use ofwater soluble adhesives for securing the filter plug and tipping paperwrappings is also known.

All of these approaches to improving the degradation of smoking articlefilters require the presence of water, such as moisture from rain, snow,dew, or residual moisture from those elements, for example, moist soil.However, in arid countries with little rainfall, such approaches areunlikely to be effective.

A further problem is that the cellulose acetate tow commonly used asfilter material is not readily degradable or biodegradable. Thus,despite efforts to promote the dissociation of the spent smokingarticle, the filter material itself will not subsequently degrade.Therefore, much of the effort expended to reduce the environmentalburden of spent smoking articles or to make such spent smoking articlesmore environmentally compatible has been directed to improving thebiodegradability of the cellulose acetate fibres. Water soluble polymershave been used instead of triacetin which solvent bonds the celluloseacetate fibres typically used to make filters. Alternatively, solublepolymeric materials such as polyvinyl alcohol and ethylene vinyl alcoholcopolymers may be used in place of cellulose acetate. Meanwhile, atobacco smoke filter made of a creped paper manufactured from a woodpulp sheet and a tobacco filter made from a regenerated cellulose fibrebundle are also known. Compared with a filter comprising a celluloseacetate fibre bundle, these filters disintegrate slightly more readilywhen exposed to moisture.

While there are clearly environmentally preferable alternatives tocellulose acetate, degradability again generally depends on the presenceof moisture, which as mentioned previously, may be scarce in some areas.

In light of the above, at least one embodiment of the invention providesa smoking article having enhanced disintegration, dispersion and/ordegradation. In particular, at least one embodiment of the inventionprovides a filter for a smoking article which is capable of degrading inthe absence of environmental water.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, a filter for a smokingarticle is provided which comprises a vehicle containing a liquidcapable of enhancing the disintegration and/or degradation of thesmoking article.

The vehicle, which can be a capsule, may be broken or otherwise actuatedto release the liquid immediately prior to disposal of the smokingarticle, or may be broken or otherwise actuated at a later timefollowing disposal. Generally the vehicle is arranged to be actuated torelease the liquid after the smoking article has been smoked.

The vehicle can be arranged to be actuated by a longitudinal or bendingforce acting on the filter, such that, for instance, the action of‘stubbing out’ the smoking article acts to release the liquid. Theprocess of actuation of the vehicle to release the liquid maysubstantially deform the filter.

The liquid may enhance the degradation of the smoking article in one ormore of the following ways. Firstly, the various components of thesmoking article may be induced by the liquid to dissociate, resulting intheir increased exposure to the environment and accelerated dispersionand biodegradation. Secondly, the degradation of one or more of thecomponents of the smoking article may be directly enhanced by theliquid. For example, the filter may comprise a filter material which maybe degraded by the liquid carried in the vehicle. Thus, for instance,when a capsule containing the liquid is broken, the liquid is released,and the degradation of the filter material is enhanced.

According to a second aspect of the present invention, a smoking articlecomprising a filter as described herein is provided.

According to a third aspect of the present invention, the use of acapsule containing a liquid for enhancing the disintegration and/ordegradation of a smoking article is provided.

According to a fourth aspect of the present invention, a method ofenhancing the disintegration and/or degradation of a smoking article isprovided wherein the smoking article comprises a capsule containing aliquid capable of enhancing the disintegration and/or degradation of thesmoking article.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is made to theaccompanying schematic drawings which each illustrate a longitudinalcross-section of an individual filter cigarette comprising a filteraccording to embodiments of the invention (not to scale).

FIG. 1 shows a filter according to one embodiment of the presentinvention.

FIG. 2 shows a filter according to an alternative embodiment of thepresent invention.

DETAILED DESCRIPTION

The present invention provides a filter for use in a smoking article,comprising a vehicle containing a liquid capable of enhancing thedisintegration, dispersion and/or degradation of the smoking article.The vehicle is preferably resistant to manipulation during use of thesmoking article, and is intended to be actuated upon disposal of thesmoking article to release the liquid contents into the filter. Thedisintegration and degradation of the filter may occur directly, forexample, by the dissolution or dispersion of one or more of thecomponents of the filter, such as the filter material, in the liquid.Alternatively, the enhancement of degradation may be indirect, forexample, as a result of increased environmental exposure resulting fromthe accelerated dissociation of the filter by the liquid.

FIG. 1 shows a smoking article 1 comprising a filter 2. The filter 2comprises two sections of substantially cylindrical filter plug 3,separated by a cavity 6. The filter plug and cavity are wrapped in aplugwrap 4. A capsule 5 comprising a liquid is situated within thecavity 6 of the filter 2. The smoking article further comprises acylindrical rod of smokeable material 7 aligned with the filter 2 suchthat the end of the smokeable material rod 7 abuts the end of the filter2. The rod is wrapped in a paper wrapper 8, and is joined to the filter2 by tipping paper 9 in a conventional manner.

FIG. 2 shows an alternative embodiment in which corresponding featureshave the same reference numerals. This embodiment differs from thatshown in FIG. 1 in that the capsule 15 is elongate in shape. Inaddition, rather than being positioned with a cavity within the filter2, the capsule 15 is embedded within the material of the filter plug 13.

The liquid held within the capsule is capable of enhancing thedegradation of the smoking article. Consequently, the selection of theliquid is dependent upon the composition of the materials comprising theremainder of the smoking article and vice-versa. In a preferredembodiment of the invention, the liquid is water and various componentsof the smoking article are water-dispersible or wet-degradable to someextent as outlined below. In this way, the degradation of the smokingarticle is enhanced relative to an identical smoking article lacking awater-containing capsule.

In the embodiment shown in the FIG. 2, the capsule 15 is enclosed withinthe filter material 13. In some embodiments, the filter may be acomposite filter comprising multiple filter segments. For example, thefilter shown in FIG. 1 comprises two sections of filter material 3separated by a cavity 6, which contains the capsule. In furtherembodiments, the capsule may be located in a cavity formed between thefilter material and the rod of smokeable material, or the filter maycomprise more than two filter sections, and may even include multiplecavities.

In the embodiments shown in the figures, the smoking article comprises asingle capsule. In alternative embodiments, however, more than onecapsule may be used, and in such embodiments, the capsules willgenerally be held within a cavity section formed in a multi-sectionfilter.

The capsule may be inserted into the filter using any suitable method,and various methods of capsule insertion will be known to the skilledperson. Suitable apparatus may, for example, include a means forsupplying a continuous stream of filter material from a source of suchmaterial (e.g., a bale, bobbin, or the like). The apparatus may furtherinclude a capsule insertion unit for inserting or depositing theindividual capsules at predetermined intervals within the filtermaterial. The filter material having capsules deposited therein may thenbe received into a rod-making means for providing a continuous rod whichmay subsequently be subdivided into the desired length at predeterminedintervals to form the individual filters of the invention.

Generally, prior art disclosures of capsules for use in smoking articlefilters are concerned with providing encapsulation methods aimed atreleasing the encapsulated material before smoking occurs. The capsulesare designed to resist breakage only during transport and storage, whenthe filter is not generally subject to significant external pressure.The capsule is subsequently intended to be ruptured immediately prior touse of the smoking article, and since this is the first exposure of thesmoking article to significant manipulation and external pressure, thecapsule is not necessarily required to be particularly robust.

In contrast, capsules for use in the invention are intended to be brokenafter the smoking article has been smoked, and thus are preferablycapable of tolerating a significant degree of manipulation as thesmoking article is smoked. Consequently, the capsule of the presentinvention should be more robust than those generally described in theprior art. It is important that the capsule is not accidentally rupturedbefore the smoking article is ready to be discarded. Such prematurerupture could lead to the filtration characteristics of the smokingarticle being changed and deliveries being thereby altered compared towhat is expected.

On the other hand, it is important that the capsule is not overly robustas it should be easily breakable after smoking ceases, during the manualextinguishing process or ‘stubbing out’. The capsule for use in thepresent invention may, for example, have a crush strength of between 1.5and 2.5 kp, preferably between 1.7 and 2 kp.

The capsule may be designed and inserted into the filter in such a waythat the capacity to rupture is dependent upon the nature of thepressure exerted. Pressure exerted by the user during smoking willpredominantly be exerted by the fingers and mouth to the circumferentialsurface of the smoking article (“transverse” pressure). In someembodiments of the invention, the capsule is to be relatively resistantto transverse pressure to prevent premature rupture. On the other hand,the stubbing out process is likely to involve the application of“longitudinal” pressure along the length of the smoking article, andconsequently the capsule should demonstrate a relatively reducedresistance to breakage in response to longitudinal pressure.

This directional capsule resilience may be achieved in a number of ways.For example, the capsule may be elliptical or ovoid and consequentlydemonstrate an increased resistance to rupture when pressure is exertedin one direction versus another. Alternatively, directional resiliencemay be achieved using a capsule which has been specifically strengthenedin certain areas. Such a capsule may be produced, for example, having anincreased shell thickness in selected areas. Naturally, a similar effectmay be achieved by weakening the capsule wall in certain areas, tofacilitate breakage or rupture in response to force being applied in aparticular manner or direction.

The stubbing out process can also involve bending of the filter.Therefore, in some embodiments the capsule is designed to demonstrateincreased susceptibility to rupture when the filter is bent or buckled.For example, a long cylindrical capsule may be used which may beruptured by being snapped. Such elongate capsules will be positionedlongitudinally within the filter, so that they are easily bent andruptured when the filter of the smoking article is stubbed out and bent.

Various means of encapsulating substances, particularly liquids, forrelease in smoking article filters are known, and are generally suitablefor use in the invention. Clearly, one of the primary considerations isthat the capsule should generally be resistant to the degrading actionof the intended contents. The capsule should also comprise materialwhich has a melting point above the temperature of the smoke within thefilter.

The capsule may exhibit brittleness under stress and/or may comprise aline of weakness, such as a scored line, a brittle point, or a weaksection. Alternatively, a piercing means may be incorporated within thefilter.

In preferred embodiments, the capsule is constructed from a frangiblematerial. In one embodiment the capsule is composed of a low solubility,high molecular weight polyvinyl alcohol. A number of suitablealternative materials are known, and by way of example, capsulestypically utilized in the pharmaceutical industry may be used. Suchcapsules may be gelatin based, for example, or may be formed from apolymeric material, such as modified cellulose. One type of modifiedcellulose which may be used is hydroxypropylmethyl cellulose. Manybiodegradable materials are known which may be suitable for use in theproduction of capsules and these include high molecular weightpolyethylene glycols, polylactic acid, plastarch material,polycaprolactone, polyglycolide, a polyhydroxyalkanoate such aspoly-3-hydroxybutytate, and zein-derived bioplastics.

Alternatively, the capsule may comprise a length of thin-walled glasstubing, the ends of which may be sealed by heating or with a materialcapable of withstanding manual handling prior to and during smoking, yetwhich can be fractured after smoking. Other suitable materials includethin-walled aluminium tubing or hollow foodstuff material, such as, forexample, pasta, or extruded hollow tubing of reconstituted tobaccomaterial. The inner walls of the capsule material may advantageously becoated with a varnish or waterproof material, such as silicone, topreserve the rigidity of the capsule material by preventing absorptionof, or degradation by, the liquid contents over a prolonged period.

The capsule may alternatively be comprised of a wax, resin, natural orsynthetic gum, latex or plastic material which retains its shape andstrength at room temperature and at smoking temperature but whichfractures to release the liquid contents upon pressure applied toextinguish the smoking article. Examples of suitable waxes includebeeswax, candelilla, carnauba, Shellac wax, caranday, sugarcane wax,myrtle wax and petroleum wax.

Suitable resins include epoxy resins, terpene resins, petroleum resins,ester gum, phenolic resins and rosin based resins. Preferred gumsinclude gum arabic, locust bean, guar, alginates, carrageenan andpectin.

Preferably the substances comprising the capsule have no effect on thetaste of the mainstream smoke as smoking occurs.

The capsule may be formed in a variety of physical formations includingsingular part or multipart capsules, large capsules, small capsules,microcapsules, etc. A number of different capsule configurations aresuitable for use in the invention; for example, the capsule may begenerally spherical (as shown in FIG. 1), ovoid, ellipsoidal (as shownin FIG. 2), cylindrical, or may approximate to a polygonal prism inshape.

The capsule may be coloured. For example, the capsule may comprise acolouring agent. The colouring agent may be used to render more easilythe location of the capsule within the filter during the manufacturingprocess. Alternatively or additionally, the colouring agent may providean interesting and attractive appearance to the smoking article,particularly if the capsule or capsules are intended to be onlypartially enclosed within the filter material, or if the tipping paperis intended to have a transparent window portion.

Alternatively or in addition, the liquid held in the capsule may becoloured. This would give the user an additional, visual indication thatthe liquid has been successfully released and that degradation of thespent smoking article will be enhanced. A coloured liquid also has theadded benefit that it could act as an indicator when the capsule isaccidentally ruptured before smoking. The colour would be a warning tothe smoker that the smoking article has been damaged and should not besmoked.

The size of the capsule is clearly dependent on the volume of liquidrequired, but consideration should be given to the fact that thepresence of the capsule in the filter should not have an adverse effecton the filtration or draw characteristics of the filter.

In one preferred embodiment, the capsule is 5 mm in diameter. Generally,the diameter of the capsule may be up to 80% of the diameter of thesmoking article. Preferably the capsule diameter is up to 70%, up to60%, or up to 50% of the diameter of the smoking article. For example,the diameter of the capsule may be between 2 and 7 mm, and preferablythe diameter is between 4 and 6 mm.

The capsule should be large enough to accommodate sufficient contents toenhance the degradation of the smoking article. The volume required willvary according to the nature of the liquid held within the capsule, thecomposition of the remainder of the smoking article and the associatedcapacity of the liquid to enhance the degradation of the smokingarticle. The volume of the capsule may be up to 60%, up to 50%, up to40%, or up to 30% of the total volume of the filter. The requirement fora large volume of liquid should be balanced, however, with the need toretain sufficient filter material within the filter to provide therequired degree of filtration.

While it is preferable for the volume of the capsule to be as large aspossible, as the size of the capsule is increased, the risk of prematurebreakage of the capsule is also increased. Furthermore, the larger thecapsule, the greater is the obstruction to the smoke flow path.Consequently, to accommodate the required amount of liquid, it may bepreferable for the filter to comprise two, three, four or more capsules.Multiple capsules may be positioned, for example, at regularly spacedintervals along the length of the filter. Alternatively, multiplecapsules may be situated as a cluster within the filter, for examplewithin a cavity formed between two sections of filter material.

Alternatively, long cylindrical or ellipsoidal capsules (or tubes) maybe used, having a length equal to a significant proportion of the lengthof the filter, or even equal to the entire length of the filter. Suchcapsules may be up to 5 mm in diameter.

Multiple capsules may be used comprising different liquids.

In some embodiments, the capsule or capsules may be further encapsulatedin a second capsule, or a sheath, or the like. This may allow greaterprotection from accidental or premature breakage, or incidental leakage.In this way, single wall or multi-wall capsules may be used to tailorcapsule stability, strength, rupture resistance, processing ease infilter making, etc.

The capsule may be manufactured using any suitable method, the method ofmanufacture of the capsule clearly being dependent on the precisecomposition and make-up required. Various methods of capsule manufacturewill be known to the skilled person, including techniques such asco-extrusion, spin coating, coacervation, interfacial polymerization,solvent evaporation, and annular jet forming.

In some embodiments in which the capsule is a seamless capsule, thecapsule may be produced using a co-extrusion process. The co-extrusionprocess is a synchronous extrusion of the two liquids that willsubsequently form the shell and the capsule contents (or “core”). Thefirst (co-extrusion) step involves forming a droplet having the liquidcore material inside the liquid shell material. After the co-extrusionstep, the “capsule” is solidified by cooling or by immersion in a curingagent, for example. The capsules may then be subjected to varioustreatments, such as washing, removal of surplus liquid, colouring,application of additional coatings, etc.

Alternatively, an annular jet forming technique may be used. This methodutilises two concentric jets to eject an inner jet of liquid corematerial and an outer jet of liquid shell material. The fluid streambreaks into droplets and the liquid shell material solidifies by phasetransition induced by the presence of cross-linking ions, pHdifferences, temperature changes, etc.

In some embodiments in which the capsule comprises a wax capsule, thecapsule may be formed, for example, by a method comprising freezing asolution of the liquid core material until small crystals are formed.According to this method, the crystals are then dropped into molten waxand removed by spatula after a wax coat has formed around the coldcrystals. The frozen core material gradually becomes liquid as thecoated capsule reaches room temperature.

In alternative embodiments, the capsule may be manufactured in situ. Forexample, in embodiments in which the capsule comprises a longcylindrical capsule extending the entire length of the filter, thecapsule may be constructed by crimping a continuous tube intofilter-length fragments as part of the filter manufacturing process.

The liquid held within the capsule may be any liquid capable ofenhancing the degradation of one or more of the materials comprising theremainder of the smoking article. Clearly the nature of the liquid isdependent upon the composition of the materials of the smoking articleand vice-versa.

The disintegration and/or degradation of the smoking article may beenhanced in one or more of the following ways. Firstly, the dissociationof the smoking article may be enhanced, resulting in the individualcomponents having greatly increased exposure to the environment and thusbeing susceptible to accelerated degradation. Secondly, the degradationof one or more of the individual components may be directly enhanced,for example one or more of the components may be soluble or otherwisereactive with the liquid held within the capsule.

Smoking articles generally comprise a number of different papers(tipping paper, plugwrap, and tobacco wrapping paper) which bind thevarious components of the smoking article and hold them together. Insome embodiments, the dispersion of the adhesive which binds thesepapers, and/or the papers themselves is enhanced by the action of theliquid in the capsule. In one preferred embodiment the liquid is water,the adhesive is a water-soluble or a water-dispersible adhesive, and theplugwrap and tipping papers comprise moisture disintegrative papers.Thus, when the capsule is ruptured, the water acts on the adhesive, theplugwrap, and the tipping paper, enhancing the dissociation of thesmoking article and accelerating the environmental degradation of thevarious components of the smoking article.

There are a number of means by which the liquid may enhance thedegradation of the smoking article. When the capsule is ruptured, theliquid is released and is able to migrate throughout the smokingarticle. In some embodiments, the liquid held within the capsule is anaqueous solution, and one or more of the remaining components of thesmoking article are in some way water-degradable, for example, composedof water-soluble or water-dispersible material. In one embodiment, theliquid within the capsule is water, and the filter material is awater-soluble or water-dispersible material, such as polyvinyl alcohol.

In alternative embodiments, other liquids may be used in the capsule,and clearly the selection of liquid to be used is dependent on thecomposition of the other components of the smoking article.

Generally the preferred liquids for use in the capsule are aqueoussolutions, and the most preferred liquid is water. Weak acidic or basicsolutions may be used. In general, any liquid may be used that is notpotentially toxic or harmful to the user. In case of the accidentalpremature breakage of the capsule, it is also important that none of theother components of the smoking article degrade to yield products whichare potentially toxic or harmful to the user.

The liquid may be coloured. This may serve as a visible indication thatthe capsule has been ruptured, which may be important for two reasons.Firstly, this will inform the user if the capsule is prematurely broken,thus alerting the user that the smoking article should not be smoked.Secondly, when the user is attempting to break the capsule, this willserve as confirmation to the user that the capsule has indeed beensatisfactorily ruptured. The interesting possibility of observing acoloured liquid may also serve as an incentive to encourage users tobreak the capsule upon disposal of the smoking article.

In some embodiments, the degradation of the smoking article is enhancedby means of a chemical reaction between the liquid and one or more ofthe remaining components of the smoking article, such as the filtermaterial. The chemical contained within the capsule may be selected toreact specifically with the particular component of the smoking article.Alternatively, the chemical may show a less selective capacity tochemically react with and degrade the smoking article, for example thechemical may be a weakly acidic solution.

The filter may comprise two or more capsules containing differentliquids. The different liquids may react together or otherwise combineto form a liquid capable of enhancing the degradation of the smokingarticle. Alternatively, different components of the smoking article maybe subject to degradation by different liquids.

In some embodiments, the capsule contains a solution which acts as anattractant to microorganisms, insects, or other organisms. Thus, therate of degradation of the smoking article is effectively enhanced bythe action of the living organisms.

According to these embodiments, the capsule may contain anenvironmentally acceptable aqueous solution of, for example, glucose (orother sugar solution), salt (as a saline solution), or starch (as a thincorn starch syrup). The skilled person will be aware that in all ofthese embodiments the selection of the materials comprising the reminderof the smoking article is important to promote the action of themicroorganisms.

The capsule is intended to be ruptured upon disposal of the smokingarticle, and frequently, spent smoking articles are associated withundesired odours. Therefore, in addition to the degrading action, theliquid may additionally possess deodorising qualities. Alternatively,individual degrading and deodorising liquids may be incorporated intothe filter in separate capsules, to be ruptured simultaneously.

The deodorising agent may be a neutralising agent or a masking agent, orbe a combination of neutralising and masking agents.

Preferred deodorisers include 2-trans-3,7-dimethyl-2,6-octadien-8-ol(often known as geraniol), 1-carvone, 1-carveol, terpinyl acetate,geranyl propionate, citronellyl butyrate, citral, cis-3-hexenol,triacetin, benzyl benzoate, acetone, safrole, terpinyl propionate,methyl salicylate, hexyl cinnamic aldehyde, isopropyl alcohol,triethylglycol diacetate (TEGDA), OdorGone™, methyl cinnamaldehyde,linalyl propionate, acetic acid, citronellal, citronellyl formate,geranyl formate and linalool. Mixtures of these compounds are alsosuitable. Many other masking agents, such as perfumes, e.g. essentialoils used in pot pourri, are also suitable compounds for use in thepresent invention.

The filter material used in the filters of the vast majority ofcurrently available smoking articles is composed of cellulose acetatefibres and does not readily disintegrate or biodegrade.

The filter material of one embodiment of the invention is composed ofpolyvinyl alcohol. Polyvinyl alcohol is commercially available as athermoplastic, water soluble, solid polymer that is relativelyinexpensive and non-toxic. Polyvinyl alcohol is unique in being the onlybiodegradable, carbon-carbon backbone polymer capable of completebiodegradation under environmental conditions. Thus, in the embodimentshown, when the spent smoking article is discarded, the user rupturesthe capsule, for example by squeezing the filter, or by stepping on thespent smoking article. This releases the water contained within thecapsule, which migrates throughout the filter, and promotes thedegradation of the polyvinyl alcohol filter material.

In alternative embodiments, other water-degradable substances may beused, such as starch, ethylene vinyl alcohol copolymers, polylacticacid, creped paper manufactured from a wood pulp sheet, or a regeneratedcellulose fibre bundle.

As described above, the liquid may not act to dissolve the filtermaterial, but may enhance the degradation of the smoking article viasome other mechanism. For example, in some embodiments, the filtermaterial may be cellulose acetate which has been manufactured using awater-soluble plasticizer to bind the cellulose acetate fibres.According to these embodiments, the liquid may be water, and othercomponents, such as the plugwrap, tipping paper, and/or adhesive, mayalso preferably be water-soluble or water-dispersible. Consequently,rupture of the capsule results in dissociation of the components of thefilter, including dispersion or dissolution of the plasticizer. As aresult, the cellulose acetate fibres are no longer bound to one anotherand the filter material disintegrates and the individual celluloseacetate fibres are able to disperse. As an alternative to the use of awater-soluble plasticizer, non-woven or loose processed celluloseacetate fibres may be used.

In embodiments in which the liquid promotes the dissociation of thecomponents of the smoking article, the filter may further comprise amaterial or powder which is capable of expansion upon the action of theliquid. In this way, rupture of the capsule results in expansion of thissubstance and consequent rupture of the filter. Suitable materialscapable of expansion will be known to the skilled person. For example,materials which will swell upon contact with water include carboxymethylcellulose, water-dispersible starch, chemically modified starch, andsuper absorbent polymers such as a cross-linked copolymer of acrylicacid and sodium acrylate or a cross-linked copolymer of acrylamide andpotassium acrylate. These materials may be incorporated into the filter,for example in powder form, and will swell when exposed to water, forexample water from the capsule of the invention. The swelling actionphysically separates the components of the filter, enhancingdisintegration of the structure and dispersion of the components.

In other embodiments, the liquid may be an aqueous solution comprisingbiological agents capable of degrading the cellulose, such as cellulaseenzymes.

In some embodiments, the filter material may comprise paper. The liquidmay be water, which will not dissolve paper but will neverthelessenhance its disintegration and degradation.

Filter materials may be used which are not biodegradable per se but maybe disintegrated or converted into a biodegradable form by the action ofa particular chemical held within the capsule.

Many smoking articles are configured to entrain a flavourant within thesmoke that is drawn along the smoking article by the user. This isfrequently achieved by the incorporation of flavourant-containingcapsules within the smoking article filter. In such smoking articles,encapsulation prevents the volatile flavourant from evaporatingprematurely, with the capsule being ruptured to release the flavourantprior to use of the smoking article. This method of flavouring smokingarticles is not obviously compatible with the degradable smokingarticles described herein, however. This is due to the abundance ofcapsules that would be required in the filter, and the fact that theflavourant capsules should be ruptured prior to smoking, whereas thecapsules of degrading liquid should be broken upon disposal of the spentsmoking article.

Consequently, in some embodiments of the present invention, the filtermay comprise a thread passing along a longitudinal axis of the filterfrom the tobacco rod end to the mouth end. According to theseembodiments, the threads are loaded with aromatic or flavourantmaterial. Thus, as smoke is drawn along the smoking article, flavourantheld within the thread becomes entrained in the smoke. The use of aflavourant-enriched thread also provides a simple means of incorporatingflavourant into the smoking article filter, requiring minimalmodification of the manufacturing process.

As used herein, the term “flavour”, “flavouring”, and “flavourant” referto materials which may be used to create a desired taste or aroma.Preferred flavourants include extracts (e.g., licorice, hydrangea,Japanese white bark magnolia leaf, chamomile, fenugreek, clove, menthol,Japanese mint, aniseed, cinnamon, herb, wintergreen, cherry, berry,peach, apple, Drambuie, bourbon, scotch, whiskey, spearmint, peppermint,lavender, cardamon, celery, cascarilla, nutmeg, sandalwood, bergamot,geranium, honey essence, rose oil, vanilla, lemon oil, orange oil,cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, piment,ginger, anise, coriander, coffee, or a mint oil from any species of thegenus Mentha), flavour masking agents, bitterness receptor siteblockers, receptor site enhancers, sweeteners (e.g., sucralose,acesulfame potassium, aspartame, saccharine, cyclamates, lactose,sucrose, glucose, fructose, sorbitol, or mannitol), and other additivessuch as chlorophyll, minerals, botanicals, or breath freshening agents.They may be imitation, synthetic or natural ingredients or blendsthereof.

The preferred material for the manufacture of the thread is cotton,although other materials such as cellulose acetate and rayon, or naturalmaterials such as plant fibres, may also be used. According to theseembodiments, the liquid held within the capsule may be capable ofdegrading the flavourant-enriched thread.

In some preferred embodiments of the present invention, moisturedisintegrative papers are used as the plugwrap, tobacco wrapping paperand tipping paper. Thus when the capsule is ruptured, water is released,and the degradation of the paper wrappers is enhanced, promoting thedissociation of the smoking article.

In alternative embodiments, one or more of the papers used in thesmoking article may not be disintegrated by water, but may be otherwisebiodegradable. In other embodiments, one or more of the papers are notbiodegradable per se but may be disintegrated by the action of aparticular chemical held within the capsule, such as a weakly acidicsolution, for example.

In order to produce an unusual visual effect, in some embodiments, thefilter comprises a transparent window which allows visualisation of thefilter material and/or capsule within the filter. In some suchembodiments, the capsule is held in a cavity formed between two piecesof filter material and the transparent window is aligned with the cavitysection of the filter material. In this way the user is provided withthe unusual effect of being able to visualise the capsule within thefilter, and this may serve as a reminder to break the capsule once thesmoking article has been smoked. To produce the effect of a transparentwindow, the tipping paper may comprise a single piece of transparentmaterial, which can be, but is not limited to, one of polypropylene,polyvinyl chloride (PVC), cellulose acetate film, polyethyleneterephthalate (PET), polyethylene oxide (PEOX), polyethylene,cellophane, Natureflex™, polylactic acid, plastarch material,polycaprolactone, polyglycolide, a polyhydroxyalkanoate such aspoly-3-hydroxybutyrate, and zein-derived bioplastics. The tipping paperhas an opaque coating on certain portions to leave a transparentuncoated section which defines the window. Since the material will be incontact with moisture from the user's mouth and fingers, the transparentmaterial used is either insoluble, or is treated with a water-resistantexternal coating. According to these embodiments comprising atransparent material, the liquid held within the capsule may be capableof degrading the transparent material.

Adhesive is generally used to bond the seams of the plugwrap, tippingpaper, and cigarette paper of a smoking article. In preferredembodiments of the invention, water-soluble or water-dispersibleadhesives are used. Water released from the capsule when it is rupturedcauses loss of the bonding between the various components of the smokingarticle, resulting in the individual components having greatly increasedexposure to the environment, and thus being susceptible to accelerateddisintegration and biodegradation.

The preferred water soluble adhesives for the seam adhesives are liquidstarch adhesives. Hot melt adhesives, or EVA and PVA adhesives may alsobe used.

In some embodiments, one or more of the adhesives used are not watersoluble. In this case, a solvent is held within the capsule which actsto soften or solubilise the adhesive, promoting disintegration of thesmoking article.

Although the vehicle containing the liquid capable of enhancing thedisintegration and/or dispersion of the smoking article has beengenerally described above as being a capsule, other fluid-containingvehicles can be used. For instance, pockets or pouches formed directlywithin a filter material or from a separate material such aspolyethylene could be used, to be ruptured once the smoking article hasbeen smoked. Also, a sponge-like porous material such as a foamedplastic polymer could be used to contain the fluid, which could bereleased via a squeezing or twisting action once the smoking article hasbeen smoked. Other suitable fluid-containing arrangements would beevident to those skilled in the art.

Above is described what is believed to be the preferred embodiment ofthe invention. However, those skilled in the art will recognise thatchanges and modifications may be made without departing from the scopeof the invention a defined in the claims.

1. A filter for a smoking article comprising a vehicle containing aliquid capable of enhancing at least one of disintegration anddegradation of the smoking article, and wherein the filter comprisesfilter material which is soluble, swellable or dispersible in water. 2.The filter according to claim 1, wherein the liquid is capable ofenhancing dispersion of the smoking article.
 3. The filter according toclaim 1, wherein the vehicle comprises a capsule.
 4. The filteraccording to claim 1, wherein the vehicle is arranged to be actuated torelease the liquid after the smoking article has been smoked.
 5. Thefilter according to claim ₄, wherein the vehicle is arranged to beactuated by a longitudinal or bending force acting on the filter.
 6. Thefilter according to claim 4, wherein actuating the vehicle to releasethe liquid substantially deforms the filter.
 7. The filter according toclaim 1, wherein the liquid enhances dissociation of components of thefilter.
 8. The filter according to claim 1, wherein the liquid is anaqueous solution.
 9. The filter according to claim 8, wherein the liquidis water.
 10. The filter according to claim 1, wherein the filtermaterial is polyvinyl alcohol.
 11. The filter according to claim 1,wherein the filter comprises a plugwrap, tipping paper and adhesive, andwherein one or more of these is soluble, swellable or dispersible inwater.
 12. The filter according to claim 1, wherein the vehiclecomprises a biodegradable material.
 13. The filter according to claim 1,wherein the vehicle comprises a capsule having a crush strength ofgreater than 1.7 kp.
 14. The filter according to claim 1, wherein thevehicle comprises a capsule having a volume of no more than about 50% ofthe total volume of the filter.
 15. (canceled)
 16. A smoking articlecomprising a filter, said filter comprising a vehicle containing aliquid capable of enhancing at least one of disintegration anddegradation of the smoking article, and wherein the filter comprisesfilter material which is soluble, swellable or dispersible in water. 17.(canceled)
 18. A method of enhancing at least one of disintegration anddegradation of a smoking article wherein the smoking article comprises afilter and a vehicle containing a liquid capable of enhancing at leastone of the disintegration and degradation of the smoking article, andwherein the filter comprises filter material which is soluble, swellableor dispersible in water.